JPH0119047B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention significantly reduces the top clearance at the top dead center of a piston in an internal combustion engine such as a direct injection diesel engine, thereby eliminating the incomplete combustion space,
That is, the present invention relates to a combustion chamber of an internal combustion engine that can reduce the dead volume.

In conventional direct injection diesel engines, etc., there are variations in the thickness of the head gasket when tightened, which is interposed between the top of the piston and the bottom surface of the cylinder head, and the thickness of the piston, piston pin, connecting rod, etc.
When taking into account cumulative errors such as dimensional tolerances of the crankshaft, etc., the piston top clearance is usually about 0.6 to 1.0 mm.

Therefore, a dead volume inevitably occurs at the top of the piston, and this dead volume hinders the improvement of combustion efficiency and causes incomplete combustion, so in order to improve the combustion efficiency of the engine, it is necessary to It is clear that it is desirable to reduce as much as possible.

In particular, in a small displacement direct-injection diesel engine, the above-mentioned disadvantages are significant, causing an increase in exhaust smoke and a decrease in engine output.

Therefore, the present invention provides a combustion engine that can reduce the dead volume of the combustion chamber between the piston and the cylinder head at the top dead center position of the piston of an internal combustion engine as much as possible, thereby reducing the exhaust smoke of the engine and improving the engine output. It provides a room.

To achieve the above object, the present invention includes, in a combustion chamber formed between a cylinder head and a cylinder of an internal combustion engine, a bead on the lower surface of the cylinder head facing the top of the piston fitted in the cylinder. This combustion chamber for an internal combustion engine is characterized in that a spacer is provided with a shaped projection, and the spacer is pressed by a piston during engine operation to reduce the dead volume within the combustion chamber.

Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 are cross-sectional views of a head gasket provided between a cylinder head forming a combustion chamber and an engine body, showing a first embodiment of the present invention. It is composed of a spacer 3 provided on one side.

The gasket body 2 is a gasket that is normally inserted between the engine body and the cylinder head.
The present invention is characterized in that the gasket body 2 is further provided with a flat spacer 3.

The spacer 3 is a flat plate 31 in which corrugated (bead-like) unevenness 32 is formed in an arc shape with a flat part 33 in between when viewed from the side.
3 are formed alternately over the entire surface of the combustion chamber 4.

The thickness T of the gasket body 2 is usually about 1.0 to 1.6 mm, and the thickness t of the flat spacer 3 is
It is about 0.2 to 0.4 mm, and the thickness H of the unevenness 32 is
It is preferably about 0.8 to 2.0 mm.

The function of the spacer 3 is to have a gap that is larger than the gap formed between the top of the piston and the bottom surface of the cylinder head in the initial stage when the piston is not in operation, and when the piston is in operation, the spacer 3 is It is necessary to keep the combustion chamber deformed under pressure to a minimum.

Furthermore, the material of the spacer 3 is such that it can deform when pressed between the piston, the top, and the cylinder head without damaging the cylinder or the cylinder head, and maintains its shape after deformation. In addition to having a certain level of strength, it is also necessary to have heat resistance and strength to withstand the high temperature inside the combustion chamber.

Specifically, stainless steel sheets with a thickness of 0.2 to 0.4 mm, heat-resistant steel sheets mainly made of nickel steel sheets,
Mild steel plates etc. are suitable.

The protrusions formed on the flat plate 31 constituting the spacer 3 may be wave-shaped, bead-shaped, or discontinuously embossed as described above.

Further, although the spacer 3 is provided in the combustion chamber to remove dead space generated therein, it is difficult to remove most of this dead space by the spacer 3 itself. Therefore, in order to compensate for this point, it is preferable to configure the engine so that this dead space is minimized when the internal combustion engine is operated.

In order to satisfy this requirement, the spacer 3 according to the present invention preferably has a corrugated (bead-shaped) or embossed cross-section as shown in FIG. Because the lower surface of the spacer 3 is formed in a concave and convex manner, the concavo-convex surface is filled with carbon fine particles generated when the internal combustion engine operates, as will be described in detail below, and the carbon particles are substantially combusted. It is possible to reduce the dead space in the room.

FIG. 3 shows a second embodiment, and in the case of the spacer 3 shown in FIG.
However, in this embodiment, a continuous wave-like unevenness 32 is formed (continuous bead shape).

Although both the embodiment shown in FIG. 1 and the embodiment shown in FIG. 2 show spacers 3 laminated on the upper surface of the gasket body 2, this lamination state is not particularly limited.

FIG. 4 shows a third embodiment, in which the spacer 3 shown in FIG. 1 is laminated on the lower side of the gasket body 2.

FIG. 5 shows a fourth embodiment. In the embodiments shown in FIGS. 1 and 4, the unevenness 32 was projected on the piston pin side, but in this embodiment, the combustion chamber Concave portion 32
a is formed.

FIG. 6 shows the general shape of a combustion chamber according to the present invention. A cylinder head 11 is stacked on top of a cylinder 10 with a gasket 1 interposed therebetween, and these are fastened with bolts. As shown in FIG. 1, this gasket 1 has a spacer 3 laminated on the upper surface of a gasket body 2, which is made of a thin metal plate and has a protrusion on the portion exposed within the cylinder bore. Further, a piston 12 is housed inside the cylinder 10 so as to be reciprocatable.

The combustion chamber according to the present invention is constructed as shown in FIG. 6, and a spacer 3 having protrusions or irregularities is provided on the upper part of the combustion chamber 4, so that an internal combustion engine having such a combustion chamber can be operated. In the initial stage of operation of the internal combustion engine, the spacer is pressed, and the carbon particles 13 contained in the combustion gas are filled between the unevenness 32 of the spacer 3 and fixed.

When the carbon particles are fixed between the unevenness 32 of the spacer 3 as described above, the lower surface of the spacer 3 becomes flat, and when the piston 12 rises, the upper surface of the piston 12 and the lower surface of the spacer 3 become flat. This will prevent a dead volume from forming between the two. Since the carbon particles adhere firmly when the internal combustion engine is operating, it is possible to substantially eliminate dead space in the combustion chamber.

Although not shown in the examples, some pistons have a depression or the like formed in the center of their upper surface in order to improve combustion efficiency. It is necessary to design a spacer structure that takes this into consideration.

According to the present invention, as in the above embodiment, the gasket interposed between the cylinder head and the cylinder body is composed of a normal gasket body and a thin metal plate, and a laminate including a spacer having a protrusion on the thin metal plate. The feature is that this protrusion can be easily deformed, and when the piston is operated, the spacer is pressed between the upper surface of the piston and the lower surface of the cylinder head to deform this protrusion. .

With the above configuration, it is possible to reduce as much as possible the gap or dead volume formed between the top surface of the piston and the bottom surface of the cylinder head when the piston rises to the top dead center, thereby increasing the compression ratio. is significantly improved compared to conventional internal combustion engines.

Therefore, an internal combustion engine having a combustion chamber according to the present invention can improve combustion efficiency and reduce harmful components in exhaust gas.

Further, when implementing the present invention, the gasket may be formed into a composite structure as described above, so that the present invention can be implemented without changing the structure of a conventional internal combustion engine.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a part of a gasket having a composite structure constituting a combustion chamber of an internal combustion engine according to the present invention;
The figure is a perspective view of the same gasket. Figures 3 and 4
5 are sectional views showing a part of gaskets showing the second, third and fourth embodiments, and FIG. 6 is a sectional view showing an example of the main part of the combustion chamber according to the present invention. be. 1... Head gasket, 2... Gasket body, 3... Spacer, 10... Cylinder, 11
... cylinder head, 31 ... flat plate, 32 ... unevenness, 33 ... flat part.

Claims (1)

[Claims] 1. In a combustion chamber formed between a cylinder head and a cylinder of an internal combustion engine, the lower surface of the cylinder head facing the top of the piston fitted in the cylinder is made of a thin metal plate, and this thin plate has a number of 1. A combustion chamber for an internal combustion engine, comprising a spacer provided with a protrusion, the spacer being pressed by a piston during operation of the engine to reduce a gap in the combustion chamber.